What is a system of equations for the following situation? There is a total of 40 questions on a test. Some questions are multip
1 answer:
First we define the variables:
m = multiple choice questions
s = short answer questions
Next we need to satisfy 2 conditions:
1) There are a total of 40 questions. We can represent this mathematically using the variables I defined:
2) The multiple-choice questions are worth 2 points and the short-answer are worth 4 points but they need to total 100 points. This can also be represented mathematically:
By satisfying the conditions provided we were able to create the 2 equations!
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The given system of equations in augmented matrix form is
If you need to solve this, first get the matrix in RREF:
- Add 2(row 1) to row 2, row 1 to -3(row 3), and 2(row 1) to 3(row 4):
- Add 11(row 2) to -5(row 3), and 19(row 1) to -5(row 4):
- Add 164(row 3) to -91(row 4):
- Multiply row 4 by 1/13080:
- Add -153(row 4) to row 3:
- Multiply row 3 by -1/91:
- Add 6(row 3) and -8(row 4) to row 2:
- Multiply row 2 by 1/5:
- Add -2(row 2), 4(row 3), and -2(row 4) to row 1:
- Multiply row 1 by 1/3:
So the solution to this system is .